The Oasis de los Osos is a sister site of the James San Jacinto Mountains Natural Reserve administered by the University of California Riverside. Los Osos is located in Riverside County about 16 km (10 miles) north of Palm Springs near the mouth of Snow Creek Canyon. Los Osos became part of the Natural Reserve System in 1987 when The Nature Conservancy deeded the land to the University of California. The 64.7 ha (160 acres) was the original homestead of Mr. and Mrs. Lamb, for whom the perennial creek on the property is named. The funds to initially acquire the property were donated to The Nature Conservancy by Mr. Robert Bear, for whom the Reserve is named (oso is Spanish for bear).
The Los Osos Reserve represents a mixture of Mediterranean and continental desert climate with warm winters of gentle rain and hot summers with violent thunderstorms. Predominant vegetation of the area consists of semi-desert shrub but the presence of a perennial water source (Lamb Creek) adds the unusual element of riparian wooded habitat.
This diversity of habitats results in a high diversity of plant and animal forms, from the aquatic to dry desert species. The site extends altitudinally 250 m (800 ft) from the valley floor up the slope of San Jacinto Peak, adding a significant elevational gradient effect to the fauna and flora found there. A recent study found one rare species, Galium angustifolium subsp. gracillimum, which had previously been collected at the Oasis in 1985 (N. Miles Fellows 160 UCR) and on the east side of Snow Canyon in 1932 (C.B. Wolf 3648 RSA-POM). Six additional rare taxa were collected east of the Oasis in Snow Canyon: Chorizanthe xanti var.leucotheca (C.B.Wolf 3677 RSA-POM), California Rare Plant Rank (CRPR) 1B.2; Erigeron breweri var. jacinteus (Mrs. C.M. Wilder 972 CAS-BOT-BC), CRPR 4.3; Linanthus maculatus (Setters & True s.n. UCR), CRPR 1B.2;Muhlenbergia californica (J.C. Roos 467 RSA-POM) CRPR 4.3; Penstemon clevelandiivar. connatus (Jim Warren s.n. UC) CRPR 4.3; and Quercus turbinella (Dick Schwenkmeyer 715 SD) CRPR 4.3). Four of these rare plants were collected prior to 1970 and have not been recollected since.
On May 25- June 3 1908 Joseph Grinnell and Harry Swarth conducted an animal survey of Snow Creek, a canyon adjacent to Oasis de Los Osos. In 2008, 2010, and 2012 the San Diego Natural History Museum was able to resurvey the area and here are their findings.
The Oasis de los Osos provides a variety of research opportunities. The high diversity of plants and animals affords many research topics. The existence of permanent water and corresponding riparian habitat adds even more research possibilities. The steep elevational change across the site and to higher slopes beyond provide an excellent venue for altitudinal studies. The Reserve is surrounded by U.S. Forest Service and BLM lands, providing even more research opportunities beyond its boundaries.
As with research, the diverse habitat and biota of Los Osos makes the Reserve an excellent outdoor classroom. Plant species from trees to flowering forbs to aquatic species offer a wide array of learning opportunities for botanical classes. Faunal species from coyotes to rodents to reptiles and amphibians will allow students to study topics in taxonomy, ecology, and evolution. Los Osos is easily accessible and relatively undisturbed and so is an ideal site to come and study desert ecology.